The historical Palakkad Fort (Tipu Sultan Fort), Palakkad, Kerala

Palakkad fort or Tipu Sultan fort. Kaazhchakal - WordPress.com
There are some historical  forts in Kerala  and among them the fort at Palakkad City is an interesting one as it has close link with the famous Mysore rulers both Hyder Ali and his son Tipu Sultan. The other fort closely linked to these rulers is the one at Dindugal, Tamil Nadu.
Standing majestically  on the lower fringes of the Sahyadri Ranges of the great Western Ghats in the heart of Pallakad  town, Kerala state  is  the  historic fort of ‘Pallakad Fort’. It also goes by the name of Tipu Sultan Fort. Believed to be one among the most well-preserved forts in the whole  of South India, perhaps next to Gingee  fort (built between 9th and 13th century) near Villupuram  and Vellore fort (built in the 16th century by the Vijayanagara rulers) at Vellore  of  Tamil Nadu, Palakkad fort  was built in 1766 AD by Hyder Ali of Mysore  whose son  Tipu Sultan was the sworn-enemy of the East India Company.  After prolonged efforts the British  killed him in 1799 at Srirangapatna, Karnataka  in the final Angelo-Mysore war. Hyder Ali  fortified the existing fort  with help from the French. The history of this fort is vague and no information  is available either on its origin or on its first builder. 
Palakkad fort/Tipu Sultan fort. LOOKERALA
In reality, the Palakkad fort had been in existence since ancient 
time  prior to the invasion of Hyder Ali and the Mysore ruler reinforced the fort to the present form to suit his needs.  The local ruler, Paliyath Achchan, under the  the Zamorin, used to pay tributes to them and later became  independent rulers  on their own before the beginning of the eighteenth century. In the aftermath of their betrayal of allegiance to the  Zemorin rulers, they became  were furious and made threats to avenge them. Fearing retribution and invasion, to  face the powerful Zamorin,  Paliyath  Achan  sought the help of Hyder Ali and sent a delegation in 1757 
to the Mysore ruler to face the imminent threats from  the  Zamorin.  Hyder Ali, being shrewd as he was, knew the strategic importance of Palakkad and its fort, seized upon the opportunity given to him on a silver platter to gain possession of a rich land. He took over the fort in the late 1750s  and till 1790 it was under his control. When his son Tipu was killed by the British toward the end of 18th century, the British - East India company  took possession of this strategically important fort.
Palakkad Fort, Kerala Kaazhchakal - WordPress.com
The history of this medieval  fort is a chequered one. From Hyder Ali the British captured the fort  in 1768  under  Colonel Wood  but, Hyder Ali did not give up his efforts and managed to recapture it after a few months.  it was retaken by Hyder a few months later. In 1783, it again changed hands  and Captain Fullerton  recaptured it  after a siege that lasted eleven days but was abandoned in the the following year. In the meantime, the Zamorin rulers took possession of the fort and it did not last long.  . At last in 1790  the fort  was finally captured by the British under Colonel Stuart. It was renovated and  strengthened to be used as   a base for military operations. For the rest of the period, the British used it as garrison until early 1900s . Later, it was converted into a taluk office. There is small shrine dedicated to god Anjaneya inside the fort. Also functioning in the fort ground are the Taluka Jail and the office of the ASI - the Archaeological Survey of India. Yet another attractions  are a  Children's park on one side of the fort an open air auditorium called  "Rappadi". 
https://en.wikipedia.org/wiki/Palakkad_Fort
www.thehindu.com/news/national/kerala/ASI-seeks-relocation-of-govt.-offices-from-Palakkad-fort/article14500851.ece